Magnesium hydroxide is an inorganic compound with the chemical formula Mg(OH)2. As a suspension in water, it is often called milk of magnesia because of its milk-like appearance. The solid mineral form of magnesium hydroxide is known as brucite.

Magnesium hydroxide is a common component of antacids and laxatives; It interferes with the absorption of folic acid and iron. [2] Magnesium hydroxide has low solubility in water, with a Ksp of 1.5& times; 10& minus; 11; All of magnesium hydroxide that does dissolve does dissociate. Since the dissociation of this small amount of dissolved magnesium hydroxide is complete, magnesium hydroxide is considered a strong electrolyte. Its low solubility makes it a weak base.